There's a sliding scale here of "amount of work" vs "amount of money received." The latter is never going to be very big, but to maximize your return you need to sell them individually, on ebay and on CL simultaneously. Other methods have been listed:
easiest - donate, take deduction
almost easiest - walk into Second Looks (I like the one up off of Anderson Ln). You'll feel violated when they tell you they'll give you about $3.50 for the lot, but at least it's something. They'll likely only want the best 20% of what you bring in. Take the rest to option 1.
moderate - list as a lot on ebay, CL. There are ebay flippers who will take it all. If you do this, take a shitpile of good pictures; you're trying to cut off all the stupid questions and make it easier on yourself.
hard - list individually on ebay, CL. Most won't sell, but there's a chance you can get a big hitter for the nicer stuff, and increase your top end. Be prepared for a thousand stupid questions, and postage + ebay fees add up over time ("free shipping" really isn't, you know).
unknown - poshmark, etsy, etc.